The Dancing with the Stars alum begins his five-episode arc on the ABC drama Sunday as Sarah's French suitor, Luc Laurent, who "could be it for her," Marini tells TVGuide.com.

"It's more than a fling. He's different than her past [significant others]. It's a beautiful relationship between them," he says. "Going into the filming of the fifth episode, there was a lot of talk of me coming back, so you may not see the last of Luc."

But we — and Rachel Griffiths' Sarah — have to meet him first, which she does while in France and it was "love at first sight." "He thinks she's very charming, intelligent, driven — something that's missing from his relationships," Marini says. "That's why he makes a dramatic move."

Not to mention a transatlantic move. The dishy Luc, who's a painter by trade, makes the trek to California to further woo Sarah and to show that he's the real deal as the Walkers contend with Kitty's cancer diagnosis. In Luc, Sarah will find a "bright light" who will challenge the way the divorced mother of two sees men as he helps her through the difficult time. That includes pitching in at home and at work, which, for the "very successful" Luc, is beneath him, Marini says."But it doesn't matter because he does everything for her because he's just madly in love with her. We concentrated on the fact that he is there for her," he says. "Sometimes people who do that are seen with an agenda, but this guy just doesn't have one. She realizes she has to look outside of the box and understand different people."But are the love and attention reciprocated? "She loves him, but she's been hurt so much that her priority is her family, so she sometimes ignores her love life," the 33-year-old says. "He will help her open up more and from that, she will understand what she needs to shift in her life to have romance."

Sarah's not the only one whom Luc wins over though. The Frenchman gets the ultimate seal of approval from the whole Walker clan, including Nora (Sally Field) after a "little misunderstanding" is squared away. "This was great because it gave me the opportunity as an actor to be one-on-one with Sally Field," Marini says. "I had such an amazing time with Sally. She's acting royalty and I'm next to her. I'm very humbled by it."Marini filmed his fifth episode last week, and the ending is left open-ended, but not "drastic or dramatic," with the possibility for a return. While specifics have not been discussed, Marini is hopeful that Luc will find a place in the Walker family portrait. "It depends on what the writers want. I believe we have an amazing chemistry and we can have a great foundation and he could be a great stepfather," he says. "Luc Laurent has all these abilities and maybe he can bring something special to the family."